Ringer apparatus



April 23, 1935; w H, EDWARDs ET AL 1,998,537

RINGER' APPARATUS Original Filed March 4, 1932 1* z mgr-mum: e/mece 5 Stop screw fiale viece y Stop screw I l v A A dapperfifimatwe F9, 7 i V Gong I I Z INVENTORS Wfifi'dwamlsfi BY JZZGIwu/L Z ATTORNEY Patented Apr. 23, 1935 UNITED STATES PATENT/OFFICE American Telephone and Telegraph Company, a corporation of New York v Original "application March 4, 1932, Serial No.

596,808. Divided and this appIicationIDecemher 11, 1934. Serial No. 757,038

.1 Claim. (01.1774);

This invention. relates to signaling systemsand more particularly to arrangements for produc-' ing improved acoustical effects from the sign lmg devices'utilized in such system This application is a division of application,

Serial No. 596,808; filed March 4, 1932 in the names 'of W. H. Edwards and J. R. Grant;

,One of the primary objects of the improved signaling arrangements of the invention consists in providing ringing signalswith an improved and more pleasant tone and lower volume of sound output in instances where themaximum ringing volume of certain existing types of equipment is not necessary. A need has been felt for such a type of signalsin furnishing telephone service, for example. for residence extension stations and relatively quiet business 'oflices. The signaling arrangements of the invention. will produce an acoustic effect far more pleasant than formerarrangements in that'the pleasing after-tones of the gongs will be preserved,"harsh and unpleasant inharmoni'c frequencies which might cause discordant effects 'will'be eliminated, and extraneous noises such as pounding or harm mering effects will be avoided. Other objects and featuresoffthe invention will appear more fully from the detailed description thereof hereinafter given.

Heretofore, when a demand existed fora signal with low volume, damped ringergongs have been used which not only reduces the volume of sound output but damps the vibration after the clapper strikes the gong. This results in eliminating the pleasing after-tones of the gongs. Another method utilized to reduce volum'eiusing the same size gongs, is-to use a metal clapper but impart to it a smaller striking force. This can be accomi plished by reducing the mass of the clapper as-L sembly or reducing its amplitude of vibration. However, with such a method although the'eifective volume is reduced, the harsh andunpleasant inharmonic frequencies produced in thegongs by the metal-to-metal contact are not eliminated and the resultant tone is notimproved... The'arrangements of the invention make. use of fnon-metallic clapper material. This elimi-r nates the metallic contactsound and in addition generates fewer inharmonic frequencies. It is pointed out that a non-metallic clapper used in' conjunction with regular ringer gongs will produce a signal of the. desired sound characteristics providing there are no other sounds produced ,bythe ringer. operation. However, there have .not heretofore been available ringer structures which do not produce considerable extraneous noise by the armature striking the pole pieces or backstop screw except the harmonic type of ringer when so adjusted that the armature does not strike the cores. However, a regular ZO-cycle harmonic ringer adjusted as pointed out above has an evenmoreobjectionable characteristic in that the clapperrests against the gongs for an appreciable interval after impact, thereby deadening certain of the vibrations and producing a hammering effect. Further: more, with the types of ringers heretofore available the pounding sounds produced by the striking of the clapper against the gongs are'trans mitted through the ringer mounting to the subscribers set and the surface to which it is attached andare apt to be very objectionable.

vIt is the primary object of the arrangements of the invention to provide a ringer which will produce an improved acoustical effect and which eliminates the unpleasant effects of ringers heretofore utilized. To accomplish the desired result the ringer of the invention utilizes a non-metallic clapper and includes among its characteristics the following features. The clapper mechanism will be so arrangedas'to strike the gongs and move away with sufiicient rapidity to avoid damping the vibrations of the gong. The armature assembly will be constructed so as to be decelerated gradually to avoid noises of impact. The mounting of the ringerin relation to the subscribers set will be so designed that it will not transmit appreciable energy at frequencies produced by. ringer operation. Other objects and features of the" invention will appear more .fully from, the detailed description thereof hereinafter given. u

The. invention may be more fully understood from the following description together with the accompanying drawing in the Figures 1 to '7 of which the invention is illustrated. In Fig. 1 is shown diagrammatically a ringer embodying the features" of the invention. Fig.2 shows in detail a portion of thearrangements of Fig.1. Fig. 3.

Y is a modificationof the arrangements of the invention as applied to a ringer of the tuned reed or harmonic type. Fig. 4 is a side elevation of the arrangement of Fig. 3. Figs. 5 to 7 inclusive are graphic illustrations of the motions of the armatures and clappers of the ringers under various conditions. Similar reference characters have. been utilized to denote like parts in all of the figures. l I

In Fig. 1 is shown a ringer embodying the 'arrangements of. the invention. The ringer coma prises the gongs! and 2, the electromagnets 3 and 4 having pole pieces 5 and 6 respectively. A clapper rod 1 is shown attached to armature 9. The clapper rod would have at its extremity a clapper 8 of non-metallic material such as raw hide or wood. The ringer would be attached to the subscribers set M by the ringer frame I2 and by the flexible or elastic washers l3 and IS. The armature arrangement is shown in more detail in Fig. 2. The armature will be provided with an elastic stop between itself and the pole piece and backstop screw. This elastic stop may consist of metallic springs, elastic cords, elastic materials, or other arrangements. The arrangement shown is an elastic material 10, such as rubber. No special fastening is necessary as the rubber tube In is normally smaller than the armature and is installed by stretching it. The wall thickness of the elastic material is such that the material replaces the present stop pin or nonfreezing disc on the under surface of the armature. A stop spring I I, which may be of copper, is provided between the stop screw and the elastic material In to prevent 'possible sticking inasmuch as the biasing spring l6 normally holds the armature against this stop. While this feature may introduce ametalllc contact, nevertheless due tcthe flexible material under .the spring II the sound at impact is not objectionable. While the elastic material has been shown as mounted on the extremity of the armature, nevertheless it may be mounted in various other ways, such as on both ends of the armature, on the armature and clapper assembly, or on the frame or other parts of the ringer.

In .Figs. 5 to '7, inclusive,.are shown curves graphically representing ringer clapper and armature motion under various conditions. In Fig. 5 curve B shows armature motion for ringers of the prior art. In Fig. 5 curve D shows armature motion for a ringer of the invention equipped with elastic stops. It will be noted from curve B that themotion of a regulararmature with regular metallic stops has an approximately rectangular characteristic indicating a very rapid acceleration and deceleration. By using elastic stops for the armature as in the arrangements of the invention, the armature motion is such that it more nearly approaches a sinusoidal characteristic, as shown by the curve D. By decelerating the armature at a slower rate near its limits of travel, the sudden impactwhich ordinarily causes sound is avoided and in addition, the energy which is dissipated at impact is stored in the elastic material and partially regained when the armature starts to move in the opposite direction. As has been heretofore pointed out one of the features of the arrangements of the invention consists in gradual rather than very rapid deceleration of the armature assembly in order to avoid noises of impact.. a

The transmission of energy from the ringer to the subscribers set, or to the article or desk, to which it is mounted is apt to produce a hammering sound. In accordance with the arrangements of the invention these hammering sounds can be eliminated or greatly reduced by providing a flexible ringer'mounting in whichvibrations are rapidly damped out. This allows the shocks generated by the ringer operation to be absorbed by the mounting and the energy dissipated without transmitting it to the set. Accordingly, the ringer is mounted with flexible. or elastic washers, such as 13 and I5, between the ringer frame I2 and the subscribersset M. This elastic insulation may take the form of rubber Washers as shown or may possible is desirable. However, too elastic a support is undesirable as it is necessary to prevent thegongs being clamped by contact with the subscribers set. This can be seen from the following formula:

where B is proportional to the energy transmitted and r is the period of natural vibration, T1 is the period of the disturbing force, and y is a damping factor.

The maximum value B may have is unity and corresponds to a very stiff mounting which would have a short period of vibration, rbeing 0. When the natural frequency of vibration is low, T is large and B which is proportional to the energy'transmitted is small.

A modified form of the ringing arrangements of the invention is shown in Figs. 3 and 4 in which a tuned reed ringer is illustrated. Fig. 3 shows a front view of the ringer. Fig. 4 shows a sideelevation of Fig. 3.. This ringer comprises the gongs 20 and 2|, the non-metallic clapper 23 andthe clapper rod 22. The clapper rod 22 is connected to a reed-mounted armature assembly 26 which is controlled by the electromagnets 24 and 25. In Fig. 4 the reed 2] is a'ffixe'd to the armature 26 by being clamped to portions 28 thereof. .The reed 21 is fastened by the members 29 to the cores of armatures of magnets 24 and Has shown in Fig. 3. As in the arrangements shown in Fig. l,

the'ringer of Fig. 3 would be connected to the subscriber's set through a flexible or elastic mounting which has not been shown. The reedmounted armature and clapper assembly is mechanically tuned. The ringer is adjusted in such a manner that the armature does not strike the pole pieces and hence armature chatter noises are eliminated entirely. To avoid a pounding noise due to the clapper damping the vibrations of the gongs by remaining too long in contact with them, the ringer of the invention will be tuned mechanically to a sufficiently high frequency, such for example, as 50 cycles, to produce a clean ring, but will be tuned electrically to the ringing frequency, such for example as 20 cycles. Thus the major motion of the clapper is at ringing frequency but when the gong is struck, a minor vibration is set up at the higher frequency and prevents the clapper from remaining against the gong. A graph of the'clapper motion is. shown in Fig. 7. It will be noted that the superimposition of the'natural. period of vibration on the major movement of the clapper will cause the clapper to move away from the gongs, as at points LM and L'M' on the curve, with sufiicient rapidity to avoid damping the vibrations of the gongs.

While the invention has been disclosed as embodied in certain specific arrangements which are deemed desirable it is understood that itis capa ble of embodiment in many and other widely varied forms without departing from the spirit of the invention as defined by the appended claim.

What is claimed is:

In a ringing signal, a gong, a synchronous operating mechanism'for said gong with a vibrating armature assembly consisting of an armature, a clapper rod and a clapper ball, and means for Cit eliminating transient vibrations set up in the operating mechanism which would tend to obscure the desired ringing sound from said gong consisting of a non-elastic stop member on the stationary portion of the mechanism, a layer of elastic material on said armature and a flexible nonelastic member adapted to partially cover said elastic material, said flexible non-elastic member being of relatively large area compared to the tributed over a large area of said elastic material 5 to reduce the unit pressure on said elastic material.

WILLIAM H. EDWARDS. JOHN ROSS GRANT. 

